Inductor-generator.



J. L. MILTON.

INDUCTOR GENERATOR.

APPLICATION FILED FEB. 12, 1907.

PatentedJune 8, 1915.

2 SHEETS-SHEET 1.

gwiwutoz Witness J v (5% {L W J. L. MILTON.

lNDUCTOR GENERATOR. APPLICATION FILED FEB. 12, 1907.

1,142,047. Patented June 8, 1915.

2 SHEETS-SHEET 2' 57 37 WSM UNITED STATES PATENT OFFICE.

JOHN L. MILTON, or omeneo, ILLINOIS, As'sIGNon or oNE-HALr r0 TOWNER K. WEBSTER, or CHICAGO, ILLINOIS.

INDUCTOR-GENERATOR.

Specification of Letters Patent.

Patented June 8, 1915;

Application filed February 12, 1907. Serial NO. 357,041.

To all whom it may concern:

Be it known that I, JOHN L. MILTON, a citizen of the United States, residing in Chicago, in the county of Cook and State of Illinois, have invented'certain new and useful Improvements in Inductor-Generators, of which the following is a specification, reference being had to the accompanying drawings.

This invention relates to improvements in inductor alternators for ignition purposes and more particularly for improvements upon similar apparatus illustrated in my Patent No. 959,95 l, dated May 31, 1910, for electric generator. Y

My improvements pertain particularly to the simplification of construction of such an electric generator, together with the building of a device, the parts of which are so correlated as to provide a mechanism of relatively high magnetic and electrical efii- 'ciency, as an entirety.

Another purpose of the invention is to construct an electric generator capable of being mounted in a protected position within the fly wheel of an engine.

Figure 1 is a side elevation of a device embodying my improvements. Fig. 2 is a section on the line 22, Fig. 1. Fig. 3 is plan view of one of the permanent straight bar magnets, detached. Fig. l is a perspective view of one of the laminated pole pieces, detached. Fig. 5 is a perspective View of the inductor shown in Figs. 1 and 2, detached. Fig. (3 is a view of a modified form of my inductor alternator mounted on the fly wheel of an engine, only a ortion of the fly wheel being shown. Fig. is an end view of theparts shown in Fig. 6. Fig. 8 is a side view of a portion of a fly Wheel carrying the inductor of my improved igniter. Fig. 9 is a section on the line 9-9, Fig; 8, the non-magnetic spider for holding the permanent magnets and pole pieces also being shown in section. Fig. 10 is a perspective view of a fly wheel carrying one of my improved inductor alternators.

In the drawings, 10 and 11 indicate oppositely disposed laminated pole pieces arranged between and in engagement with the ends of like polarity of two parallelgrcups of permanent straight bar magnets, 12 and 13. The permanent bar magnets of each group are of varying length and arranged to form a series of steps at either end of each group. The opposite ends of the laminated pole pieces 10 and 11 are correspondingly stepped, as indicated at 25, to

register and engage with the adjacent ends of the ad oining group of permanent magnets. 26 1s a. lug or projection extending over the outermost step at iaither end ofeach laminated pole piece, and forming with the said step a recess 27 for receiving one end of the outermost permanent straight bar magnet of the adjacent group.

One or more of the permanent magnets of each group is recessed at either end, as indicated at 28 in Fig. 3, to receive the adj acent laminated pole piece. 29 are wedges of suitable material interposed between the ends of adjacent permanent straight bar magnets for the purpose of holding the magnets in fixed relation to each other and snugly against the horizontal surfaces of the stepped portions of the laminated pole pieces a j acent to them.

30 are metallic binding bands or strips encircling the groups of magnets near either end thereof, and arranged to hold the magnets of the groups firmly together, It will be observed that the outermost magnet of each group is the longest and that each suc cessive magnet toward the center of the machine is slightly shorter than the adjacent magnet toward the outside. The pole pieces permanent magnets and the connecting pole pieces 10 and 11, the cross-sectional area of the pole pieces varies as the number of magnets whose flux is conveyed there: through. Thus, the transverse cross-sectional area of the pole pieces, taken in the plane of the outermost magnet, is less than the cross-sectional area taken in' the plane of the next succeeding magnet. In this way the cross-sectional area of the pole pieces varies as the number of magnets Whose flux is conveyed therethrough. In the particular embodiment illustrated in the drawings, this cross-sectional area, taken on a plane transversely of the pole pieces, is gradually di minished toward the outside of the machine until at a point opposite the ends of the outermost magnet it 1s quite small and only suflicient for the purpose of conducting the flux from this single magnet.

Each laminated pole piece has formed, preferably integrally with it, a pair of inwardly turned polar projections, those on the pole piece 11 being indicated by 11 and. 11", respectively, 10 and 10 indicating the pair carried by,.the"pole piece 10. The innermost surfaces or edges of the four polar projections are shaped or curved to form parts of the arc of" a-circle, whose center is preferably equally distant from the ends of the groups of permanent bar magnets 12 and 13.

18 is a laminated inductor mounted between the opposite pairs of polar projections, to move about an axis atright angles to the plane containing them. The said inductor is longer than it is wide and has its opposite ends curved and'shaped to move as closely adjacent to the curved edges of the polar projections as mechanical conditions will permit, without undue friction. The sides of the inductor at all points are less distant apart than points of two directly opposite polar projections, for a purpose to be hereinafter set forth.

14 is a horizontally disposed shaft to one end of which the inductor 18 is rigidly secured. This shaft may be mounted in any desired way and connected in any suitable manner to thecrank shaft of an engine. li have shown it mounted in a bearing standard 15 having an axially e xtending boss 15.

16 is a four-armed spider of non-magnetic material loosely mounted on the boss 15 and having the outer end of each of its arms preferably detachably connected to one. of thewfour'inwardly turned polar projections.

of. permanent bar magnets and the pair of laminated pole pieces, form with each other It will he noted thatthetwo parallel groups a rectangular frame and thatathe parts of 7 this. fraineare held together in normal assembled relation by means of the spider 16 of non-magnetic material. The ends of the pole pieces are held firmly pressed against the adjacent ends of permapent straight bar magnets, so as to provide a? connection between the two which will interpose in the magnetic circuit the least possible magnetic reluctance.

5;, 17 is a set screw carried by the hub of the I spider 16 and adapted to engage the boss 15' and hold the spider, and consequently the rectangular magnetic frame, in any desired position of angular adjustmen 2 1 is a coil 'of'wire relation to the polar projection 11, preferably encircling the same.

23 is a coil of relation to the polar projection 10- of the pole piece 10, and

the most-closely adjacent mg leg of the arranged in inductivecurved surfaces of wire arranged in inductiveclosely'adjacent to preferably encircling said projection. These coils connected together in any suitable way, for illustration I have shown a conductor 23 I connecting them in' series.

23 is a binding post carried by the pole piece 10, and 23 is axbinding post carried by thepole piece 11.

When possible, I have found it desirable to arrange an inductor alternator for ignition purposes of my improved form; in the fly wheel-of the engine or motor to which it is connected, in order to have it in a position in which it will be protected and at the same time will not take up any extra space.

In Fig. '6, 31 indicates the fly wheel of an engine, having spokes 31". 32 is a crank shaft bearing at the fly wheel end of an enginefcrank shaft 33. The inwardly extending part of the fly wheel hub is reduced in diameter, as indicated at 31 to receive the hub or-collar of a four-armed spider 34E of non-magnetic material, which is mounted loosely upon the said hub. 35 is a bracket for supporting the said nonmagnetic spider 34 upon the crank shaft bearing 32. The horizontal leg of this bracket is preferably held in position by the same btlts which hold the elements of the bearing 32 together. The vertically extendbracket 35 has a curvilinear slot 35 forming part of an arc of a circle struck from the axis of the crank shaft asa center. 36 is a bolt extending through said curvilinear slot and the adjacent spider arm, and 36. is a nut fitted to said bolt and adapted to bind the spider and its supporting bracket together in any position ofangular adjustment permitted by the said curvilinear slot in the bracket. In this construction the two parallel groups of permanent magnets with their laminated pole pieces connecting ends of the field magnets of like polarity, and the other elements of the device carried by the rectangular frame thus formed, are identically similar to those shown in Figs. 1 to 4 above described, and Eonsequently do not require further descripion.

37 is an inductor carried by the fly wheel 31 on its inner side and preferably formed integrally therewith, although it may be formed separately therefrom and suitably secured thereto,' if desired. As shown in Figs. 6 to Q0, inclusive, diagonally oppositely similar sector-shaped flan eser, 37 carried by the hub fly wheel and which extend out over the hub and over the collar of the non-magnetic spider thereon into the vertical'plane of the polar projections secured to the arms of the said spider, in Such manner that said oppositely disposed sector-like inductor parts, will operate as it consists of two of the the curved edges of the may be electrically the outer will permit. With this inductor,

as mechanical conditions the diagonally opposite sector-shaped portions or ends are preferably of less width at their widest point than the most closely adjacent points of two directly opposite polar projections, so that the inductor will operate with the magnet frame similarly to the inductor shown in Fig. 1.

38 is an oil cup for lubricating the bearing between the non-magnetic normally stationary spider 34: and the hub portion 31 which rotates within it.

As the two inductor alternators above described operate substantially similarly for allpractical purposes, a description of the operation of but one of them will here suflice, Assuming the inductor 18, shown in Fig. 1,

polar projections,

' to be rotating in the direction indicated by the arrow, as either of its curved ends moves immediately adjacent to the polar projections 10", 11", both of the groups of field magnets are magnetically short circuited through the polar projections 10", 11", and

z the inductor 18 entirely without the wound polar projections 10, 11", and the magnetic flux density throughthe induction coils 21, 23, is reduced to a minimum. As the inductor approaches and commences to span the polar projections 10, 11, the magnetic flux density is increased, more-or less gradually, through the coils 21 and 23, since as the inductor spans the diametrically opposite polar projections 10, 11 before it leaves the diametrically opposite polar projections 10, 11", and there are at this time paths of low magnetic reluctance both across the unwound polar projections and wound polar projections, it is conceivable that the magnetic'fiux from the upper magnet has a path of least reluctance through the polar projections 11, 10 and the inductor, and the magnetic flux emanating from the lower magnet has a path of least reluctance across the polar projections 11, 10 and the inductor. That is, during the time when the inductor spans all four polar projections, the magnetic flux from the upper and lower magnets may be considered as distributed between the induction coils, that from the upper magnet passing through the coil 21, and that for the lower magnet through the coil 23. As is well known, as the magnetic flux density through the induction coils increases current is generated in the induction windings characterizing the negative half of the alternating current Wave, and this negative half wave has a demagnetizing effeet on the permanent magnet. As the inductor 18 leaves the unwound polar projections 10", 11*, the magnetic flux from both upper and lower magnets finds a path of least reluctance through the polar projections 10*, 11 and the inductor, and there is a risein the value oi the negative half wave due to the increase at an appreciable rate of the magnetic flux density through the induction windings.

As the inductor l8 commences to leave the wound polar projections 10*, 11, the magnetic flux density through the coils 21 and 23 starts to decrease, and the positive half wave of current is generated in the coils. The maximum potential obtainable with the device herein illustrated is produced at substantially the instant the inductors 18 or 37 leave the wound polar projections 10, 11 and air gaps are established between the said polar projections and the inductors. The establishing of these air gaps of high magnetic reluctance between the inductors and the wound polar projections at either side of them, tends to cause a sudden diminishing of the magnetic flux density through the coils, the rate of decrease of magnetic flux density being very great and exceeding greatly the rate at which the magnetic flux density through the coils is at any time increased. This sudden high rate of decrease of the magnetic flux density through the induction coils is emphasized by the immediate establishing of a magnetic short circuit for the two groups of field magnets outside of said wound polar projections, namely, between the unwound polar projections 10 and 11". It will be noted that the inductors in each embodiment of my invention herein illustrated, are so shaped and correlated relatively to the polar projections, that at the instant an air gap is established between either end of one of the inductors and the polar projection 11 an air gap also exists between the opposite end of said inductor and the polar projection 11, and that the existence of the said air gaps at the desired intervals facilitates in the obtaining of the very high rate of decrease of magnetic flux density through the induction coils of which the apparatus embodying my invention is capable.

For ignition in internal combustion enadjusting the rectangular magnet frame about the axis of the inductor, the instant of generation :-of maximum potential may be varied relatively'to the position of the crank shaft for the purpose of advancing or retarding the time of ignition within the engine cylinder.

It will be noted that I have devised an inductor alternator of a high magnetic efliciency, extremely simple construction, and few parts so correlated as to be practically j conceivable, and I free from wear and tear. N0 fine mechanical workmanship and adjustments are required in its construction and for its operagion. The advantage of employing straight ar shown instead of magnets of horseshoe form, will be. at once apparent. The demagnetizing losses in bending the latter are well known, the magnetic leakage across the-air gap between the legs of such magnets is very considerable, and it would be practically. impossible to arrange two horseshoe magnets so as to form the necessary consequent poles of a device embodying my invention, without a very material magnetic leakage, outside of the area in which the inductor rotates.

Since for the reasons hereinbefore set forth the rate of decrease of magnetic flux density through the induction coils 21 and,

23, at which time the positive half wave or magnetizing wave is generated, is much greater than the rate of increase at any time of magnetic flux density through the said coils, when the negative half wave or demagnetizing wave is generated, the resultant I action,

when the apparatusis in operation, of both the magnetizing and demagnetizing current waves upon the permanent magnets will be a continual preponderating magnetizing effect upon the permanent magnets rather than a demagnetizing effect, It is have observ'edfthat this contlnual magnetizing efi'ect upon the permanent magnets will not only tend to keep the said magnets built up, but will tend to build them I saturation. v,

The arrangement of two parallel groups of permanent straight bar magnets with like poles oined by pole pieces carrying polar pro ections similarly disposed relatively to said magnets, with diagonally opposite polar pro ections wound with induction coils, and an inductor capable of movement between said pole pieces in the manner specified, all combine to produce an electric generator in whichfthevariations in magnetic flux dens1ty through the inductive windingswhich are in series are substantially uniform and s multaneous. The magnetic fields establ shed by-the permanent magnetsvat either side of the inductor oppose each other, and the pole pieces, their'polar projections, and the-lndu ctor are so-shaped and correlated as toprovide, in all operative positions of the inductor, two paths of substantiallythe same magnetic reluctance, one of said paths for the magnetic lines of force from one, and the other path for, the magnetic lines of force from t e other of said field magnets. W I V f v I \.,1-.- nation of a suitable support, a non-magnetic member carried thereby and provided with permanent magnets of the form herein up'to the-point of magnetic 1. Inafield-magnet ag-tenure, the ccniibi radially extending arms, a pair of polepieces secured to said armsv and held thereby in fixed relation to each other, a plurality of magnets having their ends connected with adjacent ends of said polepieces, and wedges inserted between adjacent magnets to hold the same firmly against the pole-pieces.

2. In the field magnet of an electric generator, the combination of a plurality of magnets, each of which is recessed at an end,, a laminated form stepped surfaces, saidmagnets being adapted to abut against said stepped surfaces, with the pole piece fitting in the repole piece cut away to of non-magnetic material, means on said pole piece overlying the end portion of the outermost magnet, and Wedges to maintain the outermost magnet against said overlying means and the remaining magnets against the stepped surfaces, substantially as described:

3. In the field magnet of an electric generator, the combination of a plurality of permanent straight-bar magnets, a pair of pole-pieces for connecting the like poles of said magnets and forming therewith a closed magnetic frame, said pole-pieces being cut away to receive the adjacent ends of said magnets, means carried by said pole-pieces and overlying the outermost'of said magnets to hold said parts in magnetic contact, wedges inserted between adjacent magnets, and means for holding said pole-pieces in fixed relation to each other.

4:. A field-magnet for an electric generator comprising two oppositely disposed groups of permanent straight-bar magnets, a pair of laminated pole-pieces connecting like polar ends of said magnets and forming therewith a substantially rectangular structure, means entirely independent of said magnets for holding said pole pieces 1n fixed relation to each other, and wedges between the magnets to maintain the saine fixed relatively to the edges of the laminations forming said pole-pieces.

5. A field'magnet structure for a machine of the character described, comprising two groups of permanent straight bar magnets a pair of pole pieces arranged between said 7 groups of magnets to form a rectangular frame and having at either endtongue and,

groove connection with; the adjacent end of the adjoining group of. magnets, and con-' stepped relation to each other, two pole the magnets of each group said groups of permanent bar magnets.

I 7. A field magnet structure for a machine of the character described, comprising two groups of permanent straight bar magnets of varying lengths and having their adjacent ends arranged in stepped relation, pole pieces, having their opposite ends correspondingly stepped and arranged between said groups of permanent straight bar magnets, and means entirely independent of said straight bar magnets for holding said pole pieces with their opposite ends, each in engagement with the adjacent end of the ad joining group of magnets.

8. A field magnet structure for a machine of the character described, comprising two parallel groups of permanent straight bar magnets, the magnets of each group being of varying length and having their adjacent ends arranged in stepped relation to each other, pole pieces, having their opposite ends correspondingly stepped, arranged between and engaging the ends of said groups of magnets of like polarity, each pole piece having at either end a recess adapted to receive the adjacent end of the outermost magnet of the group adjoining it, and means connecting said pole pieces together entirely independently of said magnets, and arranged to hold the ends of said pole pieces in engagement with the ends of said magnets.

9. In a machine of the character described, the combination of two parallel groups of permanent straight bar magnets, the mag nets of each group being of varying length and having their adjacent ends arranged in stepped relation to each other, pole pieces, having their opposite ends correspondingly stepped, arranged between and engaging the ends of said groups of like polarity, each pole piece having at either end a recess adapted to receive the adjacent end of the outermost magnet of the adjoining group, two pairs of inwardly turned polar projections, each pair carried by one of said pole pieces, an unwound inductor movable between 'said pairs of polar projections, means for holding said pole pieces in fixed relation to each other, and a coil of wire in inductive relation to one of said pole pieces.

10. In a machine of the character described, the combination of two parallel groups of permanent straight bar magnets,

' the magnets of each group being of varying length and having their adjacent ends arranged in stepped relation to each other, pole pieces, havingtheir opposite ends correspondingly stepped, arranged between and engaging the ends of said polarity, each pole piece having at either end a recess adapted to receive the adjacent end of the outermost magnet of the adjoining group, two pairs of inwardly turned polar projections, each pair carried by one of said pole pieces, anunwound inductor movable between said pairs of polar projections, a coil of wire in inductive relation to one of said pole pieces, and a spider of non-magnetic material surrounding the shaft carrying said inductor and arranged to hold the groups of permanent bar magnets and the pole pieces assembled.

11. In a device of the class described, the combination of a rotor, two sets of permanent straight-bar magnets, each set comprising magnets of different lengths, laminated soft iron pole-pieces surrounding the rotor and having stepped surfaces of en gagement, and means for holding the ends of the bar magnets in engagement with said surfaces, one set of bar magnets being placed on either side of the axis of rotation.

12. In a device of the class described, the combination of a rotor, a set of permanent straight-bar magnets of different lengths, soft iron pole-pieces having stepped surfaces of engagement, and means for holding the ends of the bar magnets in engagement with said surfaces, the cross-sectional area of the pole-pieces opposite the ends of the permanent magnets varying as the number of magnets whose flux is conveyed therethrough.

13. In a device of the class described, the combination of a rotor, a set of permanent magnets having notched ends, soft iron polepieces having stepped surfaces of engagement, and means for clamping said magnets to the pole-pieces.

14:. In a device of the class described, the combination of a rotor, a set of permanent magnets having notched ends, pieces having stepped surfaces of engagement, and bands encircling the set of magnets for clamping the same to the pole-pieces.

15. In a device of the class described, the combination of a rotor, soft iron polepieces, permanent hair magnets on either side of the axis of the rotor and arranged parallel with one another, and means for holding the ends ofthe magnets in engagement with the polepieces, the cross-sectional area of the polepieces opposite the ends of the permanent magnets varying in accordance with the flux which must be conveyed through the sections at various points.

16. A field magnetstructure comprising, in combination, oppositely disposed sets of permanent barmagnets of different lengths, a pair of pole-pieces for connecting the like poles of said magnets and forming therewith a substantially rectangular frame, said pole-pieces being provided with stepped sursoft iron pole-- faces of engagement, and means-for holding pieces having stepped surfaces of engagethe ends of said magnets in engagement with inent, said pole-pieces and permanent magsaid surfaces. nets surrounding said rotor and forming a 17. In a device of the class described, the substantially ractangular frame, the longest combination of a rotor, two sets of perma-- magnet of each set being located :farthest nent bar magnets, each set comprising magfrom the axis of the rotor, said magnets innets of different lengths, soft iron polecreasing in length as they recede from the pieces having stepped surfaces of engageaxis of the rotor, and means for holding the .ment, said pole-pieces and permanent magends of the magnets in engagement with the nets surrounding said rotor and forming a stepped surfaces of the pole-pieces, the crosssubstantially rectangular frame, the longest sectional areav of the pole-pieces opposite magnet' .of-each set being located farthest the ends of the permanent magnets varying from the axis of the rotor, said magnets as the number of magnets whose flux is conincreasing in length as they recede from the veyed therethrough.

- axis of the rotor, and means for, holding the in testimony whereof I' aflix mysignature,

ends of the magnets in engagement ,withthe in presence of two Witnesses.

stepped surfaces of the pole-pieces. I 18. 111. a device of the class described, the JOHN MHITON' combination ofa rotor, two sets of perma- Witnesses:

nent'har m ets, each set comprising mag- ER. ALEXANDER,

nets of difierent lengths, soft iron pole- SAMUEL N. Porn). 

